Bells & Yells: Ensuring safety and composure for urban cyclists

How might urban cyclists stay safe and calm in areas where pedestrians and drivers are unaware they are impeding bike lanes and paths?

Time Scope4 weeks

TeammateAmy Ashida

My RoleCoding, Circuitry, Fabrication, Usability Testing

Overview

Biking in a densely populated city like New York can feel like the most difficult level of a video game. Even when there are designated bike lanes, pedestrians often overflow from sidewalks, walking or standing in the bike lane, unaware of cyclists moving rapidly toward them. Bells are often too quiet or ubiquitous for people to hear and pay attention to, and yelling causes stress levels to rise and creates opportunities for conflict.

Our solution is Bells & Yells, a device that does the talking for us. Mounted onto the handlebars of a bicycle, it plays two distinct sounds: friendly and aggressive. On the friendly setting, sleigh bells play as a pleasant way to alert those around that the cyclist is approaching. On the aggressive setting a kookaburra bird cackle—an unusual sound outside of the jungle—plays to alert those ahead.

On the automatic setting, an infrared sensor detects the distance of obstacles from the cyclist. If someone is within 15 to 20 feet of the cyclist, Bells & Yells plays friendly sleigh bells to try and alert them. Any closer though, and it will play a kookaburra bird call. On the manual setting, the user has control of when to trigger which sound; pressing the green button emits sleigh bells, and pressing the red button plays the kookaburra bird.

Process

Sketches

Phase 1: Testing the Logic & Sensors

The first step was to figure out how the logic would work and decide on which sensors we wanted to use. Using Processing, we successfully coded the logic of playing the sounds with different inputs, which helped us understand how users would interact with the sensors and buttons.

We had originally planned to use a toggle button for the sounds, a pressure sensor for the user to manually change the sound, an IR sensor for distance, and an accelerometer as an on/off switch. In the end, we decided to use buttons instead of the pressure sensor because it would be more straight forward for the user.

Phase 2: Run Wirelessly with a Wave Shield

In order to use the device on a bike, it needed to work without being plugged into a computer. We opted for the Adafruit wave shield, which turned out to be a bigger challenge than expected. Every component of the wave shield needed to be soldered into place, the SD card needed to be formatted as FAT16 or FAT 32, and the audio files had to be 22KHz (or less), 16bit (or less) and mono. Any variations from these specifications led to malfunction, as we slowly learned. After many hours of debugging, we were able to play sounds based on button inputs, using Adafruit’s example code.

Once we were able to play sounds using the shield, we needed to move the logic that we had created in Processing into Arduino. We also needed to calibrate the thresholds of the sensor we were using so that the sounds would change in response to how close an obstacle was to the device. This resulted in a lot of trial and error, during which we learned the ultrasonic sensor we were trying to use wouldn’t work with the wave shield. With limited time, we ended up switching to an infrared sensor, and decided not to include the accelerometer.

Phase 3: Prototype 1

After we figured out the wiring, we transitioned to prototyping how the device would look and feel. We bought several boxes from the Container Store to experiment with size and shape. The one we chose had just enough room for all of the components necessary, and was long and skinny—perfect for mounting onto the handlebar of a bicycle.

We simplified our wiring and cut holes into the box to experiment with the placements of the buttons, speaker, and sensor. During this process, we learned that the box was slightly too small for all of its components. In addition to increasing the size of the next prototype, we also planned to use a smaller breadboard, and discovered the user could easily adjust the volume if we cut a slit in the box to expose the knob.

Phase 4: Prototype 2

For our second prototype we prepared a box design using MakerCase.com and Adobe Illustrator and then laser cut it onto chipboard at the Visible Futures Lab. We made a few adjustments to the case, including moving the speaker hole a few centimeters, to make room for the wave shield.

Phase 5: Prototype 3 and 3.1

The third version of our prototype included the acrylic case. Bright neon green seemed appropriate for a project like this, and adds to cyclists’ visibility and safety. Once the case was cut, we reassembled the wiring inside the new case. We hit a few snags here as some of the wires were loose. It worked well when the case was open, but it didn’t consistently work when the case. We realized the speaker protrusion interfered with the security of the wires in the breadboard. In order to address this, we went back to using a perfboard to secure the connections and free up more space for the speaker.

After soldering the wires to the perfboard, we tested Bells & Yells during a short ride in Manhattan from Chelsea to the Meatpacking District, and in Brooklyn’s Prospect Park. In the late afternoon light, Bells & Yells appears to glow, already capturing people’s attention visually. I used Bells & Yells on its manual setting, mostly pressing the green sleigh bells button, feeling too guilty to go aggressive unless it was really necessary. It was when a woman was walking ahead straight down the bike lane. She was completely bewildered by the kookaburra bird call, so it took a moment for her to move out of the way, but it was effective—and a much calmer experience than yelling at people! Reactions to Bells & Yells in and around Prospect Park ranged from laughter and smiles to nothing at all (that’s New York for you).

Challenges

Wave Shield

The biggest challenge during this process was working with the wave shield. It was difficult to find one with adequate documentation and then probably equally, if not more, difficult to get the one we chose to work properly. The documentation and examples that accompanied it were unclear, and it didn’t end up working with the longer-range ultrasonic sensor we had originally planned to use. If we were to do this again, we would try an mp3 shield instead.

Wiring

Despite hours of soldering practice we got from this project, we ran into snags as we transitioned from prototype to prototype and even place to place. The speaker we used took up a lot of room in the acrylic box, sometimes interfering with the connections of the wires. Every time we had an issue we had to walk through the wiring. In the future, we would add LEDs to help indicate what specifically needs debugging.

Future Opportunities

Bells & Yells was a fun project that could both reduce stress for cyclists and add joy to their experience biking through dense urban areas. Here are a few ideas we have for future iterations:

Improving the placement of the buttons so users don’t have to extend their thumbs as far

Adding the accelerometer on/off switch

Allowing users to customize sounds and determine what “friendly” or “aggressive” means to them

Making the product waterproof

Improving the sensor to be higher range and quality to increase sensitivity and reduce noise